Section 192.189 - Vaults: Drainage and waterproofing(a) Each vault must be designed so as to minimize the entrance of water.(b) A vault containing gas piping may not be connected by means of a drain connection to any other underground structure.(c) Electrical equipment in vaults must conform to the applicable requirements of Class 1, Group D, of the National Electrical Code, ANSI/NFPA 70.35 FR 13257, 8/19/1970, as amended by Amdt. 192-76, 61 FR 26122, 5/24/1996